Railway car draft gear



. Oct. 12, 1948. H. 1.. SPENCE 2,451,415

RAILWAY CAR DRAFT GEAR Filed July 19, 1943 2 Sheets-Sheet -1 Q I INVENTOR ATTORN EY Oct. 12, 1948. H. 1.. SPENCE RAILWAY CAR DRAFT GEAR 2 Sheets-Sheet 2 Filed July 19, 1943 INVENTOR Hubertnfence WM w ATTORNEY Patented Oct. 12, 1948 UNITED.- STATES PATENT OFFICE RAILWAY CAR DRAFT GEAR Hubert L. Spence, East Cleveland, Ohio, assignor to National Malleable and Steel Castings Company, Cleveland, Ohio, a corporation of Ohio Application July 19, 1943, Serial No. 495,239

6 Claims. 1

The Association of American Railroads during the past several years has adopted certain standards of freight car construction, including standard dimensions for draft ears and for the pocket in the underframe of the car within which the gear must operate. An A. A. R; draft gear must conform to the following dimensions: 9% maximum by 12% maximum by 24%" long, including the follower. The travel or stroke of the draft gear must be between 2 and 2%". Certain standards for draft gear performance have been adopted which among other things call for a minimum capacity of 18,000 foot-pounds when tested under the 27,000-lb. drop hammer. Several makes of draft gears conforming in all respects to the A. A. R. specifications are on the market and it has been found that they protect the car satisfactorily from the buffing and pulling shocks incident to train operation, switching and classification yards. There has, however, been a steady improvement in the handling of freight cars, due to improved air brakes, better mechanical equipment in classification yards as well as to lighter weight car design utilizing high tensile steels. In recent years the tight lock coupler has come into general service on passenger train equipment and there is a growing tendency to use a tight lock coupler or one with a greatly reduced amount of free slack for freight service. The use of any such coupler will still further improve the handling of cars and will serve to reduce the shocks which now have to be cushioned by the draft gear.

The elimination or any substantial reduction in free slack in couplers will increase the problem of starting long, heavy trains. It would probably be impossible to start a heavy train with present existing locomotives if all cars in that train had to start into motion simultaneously. The free slack existing in present couplers plus the relatively slight yield or compression afforded by the draft gears under the starting tractive effort of the locomotive, allows the cars to be started into motion serially. There is at the present time approximately 2 of relative movement between adjacent cars when subjected to the starting tractive effort of the average freight locomotive. This is made up of 1" free slack between couplers and approximately 1 of movement in the two draft gears (that is, A" movement per gear). This has been found sufficient to produce the necessary serial action in the starting of the cars of the train.

However, if tight lock couplers were to be used (in which all coupler slack has-been eliminated),

or if a substantial reduction in free slack is made, it would be necessary to provide a softer draft gear action in response to the starting tractive effort of the locomotive in order to secure the necessary serial action for starting the train. This softer draft gear action would, however, reduce the cushioning or shock absorbing capacity of the draft gear, both under buffing shock as well as under pulling action. It is not desirable, however, to make any reduction in the buff ing capacity of draft gears of the present type, for the reason that it is well known that the buffing shocks to which a draft gear is subjected are more severe than'the pulling or draft shocks. It is believed that the pulling capacity of a draft gear can safely be reduced to the extent necessary to produce the softer starting action.

I am aware that many attempts have been made to increase the buffing capacity as compared with the draft or pulling capacity of draft gears. Some of theseattempts involve a preliminary spring action in pulling, while others involve draft gears with two friction systems, one system working in pulling and the other (or both systems) working in buff. These draft gears so far as I am aware all involve non-standard car construction and nonstandard draft attachments with considerble increase in weight. Their use has therefore been very restricted.

The purpose of this invention is to produce a draft gear of A. A. R. standard dimensions and adapted for use in standard car construction and with standard draft attachments, and which will produce in buffing the'full capacity required by A. A. R. specifications, but which in draft will produce a somewhat softer action to provide sufiicient additional yielding slack to enable the starting of trains when the cars are equipped with tight lock couplers or with couplers having a substantially reduced amount of free slack.

The starting tractive effort of the average main-line freight locomotive is about 80,000 lbs. This is too great to be resisted by springs alone without considerably exceeding the dimensions Y of the present standard draft gear pocket. It is therefore necessary to make use of a combination of spring and friction.

In the standard A. A. R. vertical yoke draft rigging chosen for the illustration of the present invention, the inner or rearmost end of the draft gear moves relatively to the rear draft lugs in pull but does not move relatively to them in buff. Between the front or outermost end of the gear and the front draft lugs there is relative motion inbuff but not in draft. In all other forms of wear:- which may-rdevelop.

A. A. R. draft rigging there is relative movement between one end of the gear and some part of the car or the draft attachment (including the yoke) in pulling but not in buffing, and in my invention I make use of this selective relative movement as the means to make possible a softer gear action in pull than in buff In the drawings: V

Figure 1 isa plan view partly in sectiomshowing a draft gear embodying my invention.

Figure 2 is a view similar to Figure 1, showingthe draft gear in buff position; and t Figure 3 is a view similar to Figure 1, showing the draft gear in pulling position.

In the form chosen for illustration I have shown the A. A. R. vertical'yoke applicationdn which the rear draft lugs are shownat I, the front draft lugs at 2, these lugs being secured to the draft sills 3. The front end of the vertical yoke which receives the shank of the coupler is .shownzat-A: :andwthe rear part of the; yoke .which engages the draft :gear in pulling. is shown'zat la.

-The :draft t'gear to "which :this invention has 'heenaapplied'e is one of; the weil known; types and conslsts-of arfollower wedge: 5, friction shoesifi,

which-are wedged :against acentralfriction memher i, and forced along th friction member: in

.frictionalvcontactttherewith. The movement of the-friction shoesalong the; central friction: memhen-is: resisted by? two sets of: double-coil springs, 1

indicated 31384 transmitting their pressure against the friction FShOBS through a segment seator followerr9. Theamount: of frictional resistancefdevelope'd between theifriction shoes'rand the: frictionmemberisroughlyproportional to the pressure'withwhich:thesesprings force theshees into the followerwe'dge i.

Wherrthe gear is assembled to. its normal length and: inserted into the; gear.v pocket, these springs are 'ccompressed: slightly so as to maintain 1 thev friction parts tight and to compensate 3 for rrany In fray invent-1on1 makgtheinner coil; of each: spring shorter than the outer coil, with itsiinnermostnend (the'rend away from the coupler) seated against plunger Figure 2 shows the. draftgear partly compressed in wbuffing. The forward end of the gear .has been forcedaxawayrfrom"thefront. draft lugs and the *wedge :has moved the friction shoes along the central 3 friction member, compressing rboth inneiwandfouter coils ofthetspringsfi. "In" this action-the plungers l .asweli :as the rear or base of therdraftsgearrbear-directlyeagainst the rear Ed'raft'lugs I, thuscompressingt'bothcoilsofzthe springs 8 and forcing the; friction shoes into normal: frictional contact with; the friction member, thus iproducingtinormal buffing action.

Figure .1 3 :sshows the 'draft gear 1 :under; partial compressioniin" pulling. Theisbaclrportion 1 izz-of the yoke engages the base of the draft gear and pulls it. away. from the rear zdraft' lugs, while the forward-end of the gear. is: held from :movement bymontact with the frontdraft lugs. action compresses:v the outer :c'oils of the :springs but the plungers l0 beingffree'to movexrelatively' to the base of the gear, remain. in contact'with the rear draft lugs. 'Ihus, during this part of. the pulling movement the inner coils of the springs are not compressed, with the result that the spring pressure against the friction shoes does not :build up as rapidly. in pulling'action as it'does in the buffing action illustrated in Figure'2.

After-a predetermined amount of pulling movement the"fiange H101. on the: plunger comes'into contact with the base of the draft gear and thus limits further movement of the base relative to the plunger. At that point the plunger is forced to move with the base of the gear, thus compressing the inner coils of the springs, during the remainder of the pulling movement of the draft gear. During the release movement of the parts thexoutercoils of the-springsforce the friction 'memberand base of the-gear back to a fully released position in contact with the rear draft lugs.

Thus, it will be seen that under bufiing action both the inner and the outer spring coils are compressed during the entire buffing movement of the draftr'gear. Under pulling action the outer coils arecompressed during the entire pulling movement; whereas the inner coils are not compressed until a predetermined point has been reached in the pulling movement of the gear. Thus,"the spring pressure forcing the shoes into the follower wedge is reduced during the pulling rmovement of: the gear as ;compared with the "buffing movement, can-d consequently-the resistance offered by thezgear inpulling is decreased or lsoftene'diascomparednvitlr its normal bufiing resistance.

It is obvious that this invention'may beapplied V to other types of gears inwhichthe gear capacity is-determined by thecapacityof'thesprings which set up thefrictionalyraction. Inthe present instance Iv have-made use ofrthe relative movement in :pulling action. between "the; inner end of I the draftagear :and'therear:.draft=,

lt igobvious-thatasimilar use may bemade of therrelative movementi-betweenihe couplerr'butt and draft :gear' inrpulling, tor the relative movement between the; ldIEftfgBEIZ and other partsof the attachments :or the carstrncture which exists in pulling butrnot: in buffing.

"The termsand'expressions: which I have employed: are used .asterms ofrdescrip-tion; and not of limitatiomaandl have: nozintention; in the use of: such" terms andiexpressions, ofexcluding-any equivalents: of 1 the features 1 shown and :described or: portions thereof, but: recognize that various modifications :are possible-withinthescopesof t -e invention claimed.

=What'll'claim' is:

-15A railway-draft gear comprising -a"pair of relatively 'movable followers, aspring xmeans ..-be-

tween said followers-a friction system, certain of said spring" means" actuating said friction system throughout relative movement of said followers in draft and buff, stop means at one end of-said draftgeanand means in engagement with others of said v-.spring means and with said stop means adapted to actuatesaid friction system after a predetermined amountof relative movement of said followers in draft. 4 I

*2. A railway 'dr'aft -gear comprising-a wedge, shoes and a friction member, spring means acting on said shoes 'for urging said shoes-into engagement with said-wedge and friction member throughout closure of ;said draft gear in "buff an'd 'd1iaft, abutment means at one end of said draftgear, and=means comprising'other spring means between said shoes andsaid abutment means exerting aconstant pressure-against said shoes 'for-a partof the closure of-said draft member, spring means reacting at one end on said shoe for urging said member and shoe into frictional contact, abutment means engaging the other end of said spring means and slidably as sociated with said friction member, said abutment means being normally adapted for engagement with the rear draft lug of a car, and means for moving said friction member relatively to said abutment means in draft so as to cause said spring means to act with a constant force against said shoe during a portion of the travel of said gear in draft, said abutment means being adapted to engage the rear draft lug throughout the travel of said gear in buff to cause said spring means to act with increasing force against said shoe during travel of said gear in buff.

4. A friction draft gear comprising a friction system and spring means for actuating said friction system, certain of said spring means acting against said friction system when said draft gear is compressed in buff or draft, abutment means at one end of said draft gear movably associated with said friction system, and others of said spring means engaging said abutment means, said abutment means remaining stationary when said draft gear is compressed a predetermined amount in draft and being movable with said friction system during the remainder of said movement and causing said last-named spring means to act against said friction system with constant force during said predetermined movement in draft and with increasing force during the remainder of said movement.

5. In a railroad car, a draft gear pocket, a friction draft gear within said pocket, a yoke surrounding said draft gear and connected to a car coupler for actuating said gear in draft and. bufi, spring and friction means in said draft gear, certain of said spring means acting against said friction system and a part of said pocket so as to exert a force against said friction means proportional to the movement of said gear in said pocket in one direction, and spring controlling means between said draft gear and pocket slidably associated with said draft gear, said last-named means being adapted to move with respect to said draft gear for a part of the travel thereof so as to cause said spring means to exert a force on said friction means an amount not proportional to the movement of said draft gear in the other direction.

6. A friction draft gear comprising a friction member having a base, a friction shoe slidably associated with said member, a wedge member engaging said shoe and movable relative to said member, spring means for resisting movement of said wedge relative to said member, a plunger movable a predetermined amount with respect to said base of said member in a direction lengthwise of the draft gear, the end of said plunger normally engaging the rear draft lug of the draft gear pocket of a railway car, and other spring means reacting between said plunger and said shoe for resisting movement of said shoe relative to said member, said plunger remaining in engagement with said rear draft lug during movement of said plunger with respect to said base said predetermined amount during closure of said gear in draft, thereafter said plunger engaging said base and traveling therewith during further closure of the gear.

HUBERT L. SPENCE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

